﻿using System;
using System.Collections.Generic;
using System.Linq;
using BepInEx.Configuration;
using BepInEx.Logging;
using UnityEngine;
using Logger = BepInEx.Logging.Logger;

namespace BepInEx.Unity.Mono.Configuration;

/// <summary>
///     A keyboard shortcut that can be used in Update method to check if user presses a key combo. The shortcut is only
///     triggered when the user presses the exact combination. For example, <c>F + LeftCtrl</c> will trigger only if user
///     presses and holds only LeftCtrl, and then presses F. If any other keys are pressed, the shortcut will not trigger.
///     Can be used as a value of a setting in <see cref="ConfigFile.Bind{T}(ConfigDefinition,T,ConfigDescription)" />
///     to allow user to change this shortcut and have the changes saved.
///     How to use: Use <see cref="IsDown" /> in this class instead of <see cref="Input.GetKeyDown(KeyCode)" /> in the
///     Update loop.
/// </summary>
public struct KeyboardShortcut
{
    static KeyboardShortcut()
    {
        TomlTypeConverter.AddConverter(
                                       typeof(KeyboardShortcut),
                                       new TypeConverter
                                       {
                                           ConvertToString = (o, type) => ((KeyboardShortcut) o).Serialize(),
                                           ConvertToObject = (s, type) => Deserialize(s)
                                       });
    }

    /// <summary>
    ///     Shortcut that never triggers.
    /// </summary>
    public static readonly KeyboardShortcut Empty = new();

    /// <summary>
    ///     All KeyCode values that can be used in a keyboard shortcut.
    /// </summary>
    public static readonly IEnumerable<KeyCode> AllKeyCodes = (KeyCode[]) Enum.GetValues(typeof(KeyCode));

    // Don't block hotkeys if mouse is being pressed, e.g. when shooting and trying to strafe
    private static readonly KeyCode[] _modifierBlockKeyCodes = AllKeyCodes.Except(new[]
    {
        KeyCode.Mouse0, KeyCode.Mouse1, KeyCode.Mouse2, KeyCode.Mouse3, KeyCode.Mouse4, KeyCode.Mouse5,
        KeyCode.Mouse6, KeyCode.None
    }).ToArray();

    private readonly KeyCode[] _allKeys;

    /// <summary>
    ///     Create a new keyboard shortcut.
    /// </summary>
    /// <param name="mainKey">Main key to press</param>
    /// <param name="modifiers">Keys that should be held down before main key is registered</param>
    public KeyboardShortcut(KeyCode mainKey, params KeyCode[] modifiers) : this(new[] { mainKey }.Concat(modifiers)
                                                                                    .ToArray())
    {
        if (mainKey == KeyCode.None && modifiers.Any())
            throw new
                ArgumentException($"Can't set {nameof(mainKey)} to KeyCode.None if there are any {nameof(modifiers)}");
    }

    private KeyboardShortcut(KeyCode[] keys)
    {
        _allKeys = SanitizeKeys(keys);
    }

    private static KeyCode[] SanitizeKeys(params KeyCode[] keys)
    {
        if (keys.Length == 0 || keys[0] == KeyCode.None)
            return new[] { KeyCode.None };

        return new[] { keys[0] }.Concat(keys.Skip(1).Distinct().Where(x => x != keys[0]).OrderBy(x => (int) x))
                                .ToArray();
    }

    /// <summary>
    ///     Main key of the key combination. It has to be pressed / let go last for the combination to be triggered.
    ///     If the combination is empty, <see cref="KeyCode.None" /> is returned.
    /// </summary>
    public KeyCode MainKey => _allKeys != null && _allKeys.Length > 0 ? _allKeys[0] : KeyCode.None;

    /// <summary>
    ///     Modifiers of the key combination, if any.
    /// </summary>
    public IEnumerable<KeyCode> Modifiers => _allKeys?.Skip(1) ?? Enumerable.Empty<KeyCode>();

    /// <summary>
    ///     Attempt to deserialize key combination from the string.
    /// </summary>
    public static KeyboardShortcut Deserialize(string str)
    {
        try
        {
            var parts = str.Split(new[] { ' ', '+', ',', ';', '|' }, StringSplitOptions.RemoveEmptyEntries)
                           .Select(x => (KeyCode) Enum.Parse(typeof(KeyCode), x)).ToArray();
            return new KeyboardShortcut(parts);
        }
        catch (SystemException ex)
        {
            Logger.Log(LogLevel.Error, "Failed to read keybind from settings: " + ex.Message);
            return Empty;
        }
    }

    /// <summary>
    ///     Serialize the key combination into a user readable string.
    /// </summary>
    public string Serialize()
    {
        if (_allKeys == null) return string.Empty;
        return string.Join(" + ", _allKeys.Select(x => x.ToString()).ToArray());
    }

    /// <summary>
    ///     Check if the main key was just pressed (Input.GetKeyDown), and specified modifier keys are all pressed
    /// </summary>
    public bool IsDown()
    {
        var mainKey = MainKey;
        if (mainKey == KeyCode.None) return false;

        return Input.GetKeyDown(mainKey) && ModifierKeyTest();
    }

    /// <summary>
    ///     Check if the main key is currently held down (Input.GetKey), and specified modifier keys are all pressed
    /// </summary>
    public bool IsPressed()
    {
        var mainKey = MainKey;
        if (mainKey == KeyCode.None) return false;

        return Input.GetKey(mainKey) && ModifierKeyTest();
    }

    /// <summary>
    ///     Check if the main key was just lifted (Input.GetKeyUp), and specified modifier keys are all pressed.
    /// </summary>
    public bool IsUp()
    {
        var mainKey = MainKey;
        if (mainKey == KeyCode.None) return false;

        return Input.GetKeyUp(mainKey) && ModifierKeyTest();
    }

    private bool ModifierKeyTest()
    {
        var allKeys = _allKeys;
        var mainKey = MainKey;

        var allModifiersPressed = allKeys.All(c => c == mainKey || Input.GetKey(c));
        if (!allModifiersPressed) return false;

        var noOtherModifiersPressed = _modifierBlockKeyCodes.All(c => !Input.GetKey(c) || allKeys.Contains(c));
        return noOtherModifiersPressed;
    }

    /// <inheritdoc />
    public override string ToString()
    {
        if (MainKey == KeyCode.None) return "Not set";

        return string.Join(" + ", _allKeys.Select(c => c.ToString()).ToArray());
    }

    /// <inheritdoc />
    public override bool Equals(object obj) =>
        obj is KeyboardShortcut shortcut && MainKey == shortcut.MainKey &&
        Modifiers.SequenceEqual(shortcut.Modifiers);

    /// <inheritdoc />
    public override int GetHashCode()
    {
        if (MainKey == KeyCode.None) return 0;

        return _allKeys.Aggregate(_allKeys.Length, (current, item) => unchecked(current * 31 + (int) item));
    }
}
